Question

Experiment related questions

PART 1 Data: NR= no reaction NaNO, KNO Ca(NO3)2 Mg(NO3)2 Ba(NO3)2 Cu(NO3)2 AI(NO3)3 Ni(NO3)2 AgNO3 9 NaCI NR INR NR NR INR N P milky color Nal INR NR NR autunn NR NR yellow Na2C204 millky D * 16* IP 40 * baby arolweertrade Milky obr I color IP P sade White INRP blue color P + Na2S milky ight. I black Brown on color Grey Na2SO4 I milley silver YY 7 V 7 NaOH light I grey blue grey

Answer 1

Ques 1). Which cations don't make prepicipitates with any anion?

Ans1). From the table we can see than column down to NaCl and KNO3 is filled with the result "No reaction", we can say that these two cations i.e. Na+ and K+ do not undergo precipitation with any of the available anions in the table above.

These two cations i.e. Na+ and K+ belongs to the first group of the periodic table and they are known as alkali metals.

Ques 2). Which cations form precipitates with more than or equal to four anions?

Answer 2). From the given table you can see that there are four such cations which can form precipitates with four or more anions. These cations are Ba2+, Cu2+, Ni2+, and Ag+.

Among these cations Cu2+, Ni2+ and Ag+ belongs to the d-block (transition elements) while Ba2+ is an alkaline earth metal from the second group.

Ques 3). Order of precipitation with respect to size?

Ans 3). If you consider Mg2+, Ca2+ and Ba2+ they belong to second group of the periodic table although from different periods. They are from 3rd, 4th and 5th period respectively. Down the group ionic size increases. Therefore given cations can be arranged in increasing order of ionic size as:

Mg2+ < Ca2+ < Ba2+

Also from the table the number of precipitates each of these cation forms is:

Mg2+ = two ppt.

Ca2+ = three ppt.

Ba2+ = four ppt.

Comparing with size we can state that preference for precipitation increases with increase in ionic size (i.e. down the group).

Or we can say that likelihood of precipitation is directly proportional to the size of cation.